Let's say you have a Wii in perfect working order with a bunch of saves and downloaded purchases on it. You want to buy a Wii U. Gamestop has a pretty sweet trade-in deal for going from a Wii to a Wii U. The good news is that you can in fact move all of *most* of your digital purchases from the Wii to the Wii U....something nobody was really expecting considering how screwed up the Nintendo policies are.
The bad news is that you can't possibly trade in your Wii toward the purchase of a Wii U and keep your stuff. You see, you need both systems together to make the transfer. (As outlined here)
Anyway, Nintendo continues to be ridiculously backwards when it comes to digital distribution. I mean, let's say we throw away the whole trading in one system for another thing since that probably isn't Nintendo's priority anyway. What exactly does Nintendo think is the motivator for people to buy anything from their digital store? I bought a couple of old NES games before I realized how this all works and haven't bought anything else since then. It is money down the toilet. They are the hardware manufacturer and the software distributor, so having a system where if hardware fails people have to buy the software AGAIN is really sketchy. Like mafia loan shark sketchy.